Ethylene interpolymer products are widely used in film applications. In film applications there is a need to improve film caulkability. The term “caulkability” refers to the ability of a film to seal through, or seal around contaminants. A film having good caulkability is highly desired, i.e. such films produce packages that do not leak. In the food packaging industry films that produce a packages of high integrity are valued because a package that leaks “a leaker” can be catastrophic, e.g. one leaker in a box containing multiple packages frequently results in the rejection of the entire box. In high speed packaging lines the ability of a film to seal through contamination is frequently challenged because the sealing area becomes contaminated with the food item being packaged (powders, liquids or pastes, etc.). Non-limiting examples of high speed food packaging processes include vertical and horizontal form-fill-seal packaging lines. In practice, it is common for the line speed of a packaging line to be limited by poor film caulkability. Generally, in the case of films having higher caulkability, the line speed of the packaging line can be increased (an obvious economic advantage) and fewer leakers are produced.
Herein, ethylene interpolymer products are disclosed that have improved caulkability.
The ethylene interpolymer products disclosed were produced in a solution polymerization process, where catalyst components, solvent, monomers and hydrogen are fed under pressure to one or more reactors. For ethylene homo polymerization, or ethylene copolymerization, reactor temperatures can range from about 80° C. to about 300° C. while pressures generally range from about 3 MPag to about 45 MPag and the ethylene interpolymer produced is dissolved in a solvent. The residence time of the solvent in the reactor is relatively short, for example, from about 1 second to about 20 minutes. The solution process can be operated under a wide range of process conditions that allow the production of a wide variety of ethylene interpolymers. Post reactor, the polymerization reaction is quenched to prevent further polymerization, by adding a catalyst deactivator, and passivated, by adding an acid scavenger. Once passivated, the polymer solution is forwarded to a polymer recovery operation where the ethylene interpolymer is separated from process solvent, unreacted residual ethylene and unreacted optional α-olefin(s).